Creating C++ game on my own

It's just not possible. This is not very different from someone asking in a film-making forum how many hours it would take to make a movie like "Saving private Ryan" doing all the work yourself. It's not measured in hours weeks or months, but in decades. And it assumes you are actually capable of doing game design, programming, art, composing music, etc.

Even if we assume that you are some kind of Leonardo da Vinci, there are about 60 people listed in the credits for this video game. If you imagine that they worked on it full time for around 2 years (I imagine the development time of a large videogame of that order), this comes out to about 120 years of work.

Hmm i dunno why but i don't follow why it would take so long =/ i've made similiar in flash and javascript on my own in under a year (full time in terms of working on it).

Why does C++ suddenly increase that length of time to achieve compared to other languages

The programming language have nothing to do with it, in my opinion javascript will be harder because it's such a mess to debug with it. What alvaro is trying to say is that you need more than programmers to create a successful commercial game "like age of empires", you require designers, 2d/3d artists, scenarist, sound artists, quality assurance, sales, support, and much more. I very doubt the games you made in javascript for fun is at the age of empires quality rank. You can't do that by yourself. Of course if you keep things simple and don't actually plan to do a commercial-quality game and just a quick prototype with crude graphics/gameplay, it could be possible in under a year for an experienced programmer. If you have zero experience with object oriented design, algorithms and data structure prepare to hit some big walls that might takes years to fully grasp like every programmers.

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It's definitely possible to make a RTS game in C++, if you're an experienced programmer. Difficult, yes, but possible.
Age of Empires is old... with modern tools and technology and better end-user hardware available, it's definitely possible to make a RTS of better quality than the first Age of Empires game, at least in some areas (graphics, gameplay features), but perhaps not in others (design, historic research, quality assurance).

Still, back in it's day, it was put together by a full team of 40 people. You'll be able to (if you are experienced in C++ already), come up with a impressive product if you invest 2 or 3 good years into it - but it wont be a cakewalk, there will be definite challenges that will demotivate you. And eventually, you'll need help to work on the parts of the games you yourself aren't able to (Art maybe, or music, or maybe story or interface design), but it's definitely smart to see how far you can get on your own before dragging others in.

It'll take a serious time investment, and serious self-discipline to stay focused on it even when you are unmotivated. But you are certainly able to complete such a game, programming-wise. You might want to start with an Open Source RTS engine, and build off of that. Consider checking out Spring and study how it works (ignoring the 3D part of Spring, but look at how the logic and architecture. Age of Empires was 2D).

Making a 2D RTS game will be difficult, and it will take time, but if that's what you want to do, and if you consider the time and difficulty a worthy investment to meet your goal, then go for it. I mean, that's why you're a programmer after all, isn't it? Try making a TBS game first, and see how far you get. Then try the (more complicated, but still possible) RTS game.

If the you are a new programmer, or even just new at C++, start at Tetris, and study how that works. Then Minesweeper, Asteroids, Chess, a few medium-sized projects, and then (2-4 years of experience later) start your large project. A RTS is a large project, by the nature of the genre.

If you imagine that they worked on it full time for around 2 years (I imagine the development time of a large videogame of that order), this comes out to about 120 years of work.[/quote]
You're using mythical man-month time. If it takes 20 people a year, it's a mistake to assume that it'll only take 40 people half a year. Likewise, it's wrong to assume that it'll take 10 people two years.
Also remember that game is 15 years old, and definitely shows it's age.

Why does C++ suddenly increase that length of time to achieve compared to other languages

Because C++ is lower level - you have to handle much more of everything yourself.
You're asking why flying in a plane is faster than weaving through a city in a car. Or why electronic switching systems (for telephone networks) are faster than the old manual switching systems.

If you don't already know C++, you need to spend alot of time making smaller and medium sized projects before you start working on a large project like a RTS.

if you know how to programe, and you know how to use a graphics API , around 5 years for 2 race 8 player network game with map editor, and about 20 different unit types
part time lots of hours lost my life twice doing it.

It is possible, but it will be very hard to stay motivated and focused for so long. If you said you have done such projects in other technologies, try porting one of those into C++ first, and then pick it up from there. That will give you some feedback about what it takes, giving that you already have all the assets and the game logic, it is just the technology that you want to change.